The European Pressurized Water Reactor (EPR) is the result of a joint development effort by Framatome and Siemens, and now made available by AREVA. The EPR is a very robust 1600+ MWe four-loop PWR design, with a small technology leap. In the EPR, the designers have chosen to use active safety systems and increase the redundancy in the power sources and the water inventories to manage any potential transients. The EPR also has a double concrete containment and a core catcher for the mitigation of severe accidents. The core of the EPR is designed to operate with both UO2 and MOX fuel, and is expected to provide reduced uranium consumption. The EPR has been designed to operate under load following conditions between 20% and 100% of rated generator power. The EPR includes fully digital I&C systems, but does not take advantage of modular construction and factory fabrication. EPR reactors are currently under construction in Finland, France and China, and planned in the US and India.

The concept of defence in time is much less widely accepted. However, the components of defence in time are included in many publications related to operational safety. An excellent description of operational safety prin­ciples and practice is presented in the report Management of Operational Safety in Nuclear Power Plants, INSAG-13 (1999b).

Figure 10.4 illustrates the need for defence in time. The question of needed defence begins in the immediate present. We can presume that, at this time, all plant systems are performing perfectly, in accordance with the requirements of the operating licence and in accordance with the design

Prevention

Process systems

Mitigation

Safety systems

10.3 The defence in depth concept.

Fut

10.4 The need for defence in time.

intent. Now, as the time interval beyond this instant increases, uncertainties will arise with respect to the functionality of components and systems. The future is inherently uncertain. The direct question may be ‘Should we do inspection or maintenance operations of component or system “X” at this time, or can it wait until tomorrow?’ As time passes the overall uncertainty increases regarding the plant’s performance under both normal and poten­tial abnormal operating conditions — sometimes very rapidly. The answer, of course, is careful monitoring of all systems, inspection, and maintenance. These multi-faceted actions together constitute ‘defence in time’.

Obviously, the operating crew must carry the responsibility and authority for this aspect of safety defence. Infrastructure and methodologies for car­rying out these tasks must be established before plant first begins to operate, and must be continued for the whole lifetime of the plant.

An integral part of defence in time is regular examination, throughout the life of the plant, of events in the environment around the plant and to some extent events in the whole world that might reveal important short­comings or unappreciated advantages of the plant for which the operating crew is responsible. Revisions and upgrades may be initiated based on these regular examinations.

Over the past half-century there have been important developments in the measurement of safety of complex technologies, notably aircraft and nuclear safety (Duffey and Saull, 2003; Reason, 1990; Weick and Sutcliffe, 2007). Safety (or its logical inverse, risk) is difficult to measure when it is good; that is, when nothing happens by which to measure the frequency of abnor­mal occurrences. Under these conditions it is natural for humans to con­clude that the risk is very low or zero. The second level worthy of consideration is the frequency of ‘close calls’, or situations that could have resulted in negative consequences had some fortuitous occurrence not intervened. A ‘close call’ is a clear indication of loss of defence in depth, within the safety regime applied to nuclear plant operation. A third level of defence is available through examination of the availability of ‘poised’ or operation-ready safety systems designed to mitigate the consequences of abnormal events. All of these performance indices rely on administrative attention and action by management and by independent safety auditors assigned to ensure that safety-significant events are actually observed and recorded.

Exposure levels should be controlled through dose limits, dose constraints and reference levels for representative individuals (ICRP, 2007a) and mainly throughout the full application of the principle of optimization of protec­tion. ICRP has provided ample guidance for the implementation of optimi­zation (ICRP, 1973, 1980, 1990, 2006b).

A dose limit is an individual-related dose restriction defined as the value of the effective dose or the equivalent dose to individuals from planned exposure situations that shall not be exceeded.

Dose constraints are prospective and source-related restrictions on the individual dose from a given source, which provide a basic level of protec­tion for the most highly exposed individuals from that source, e. g. a NPP in toto or any of its systems, and serve as an upper bound on the dose in opti­mization of protection for that source. For occupational exposures, the dose constraint is a value of the individual dose used to limit the range of options considered in the process of optimization. For public exposure, the dose constraint is an upper bound on the annual doses that members of the public should receive from the planned operation of the NPP.

Reference levels are used in emergency or existing controllable exposure situations, and represent the level of dose or risk above which it is judged to be inappropriate to plan to allow exposures to occur, and below which optimization of protection should be implemented. The chosen value for a reference level will depend upon the prevailing circumstances of the expo­sure under consideration. They shall be used in the emergency planning of any NPP.

Figure 11.6 contrasts dose limits with dose constraints and reference levels for protecting workers and members of the public (ICRP, 2007a).

Table 11.8 illustrates the use of dose limits, dose constraints and reference levels within the system of protection for occupational and public exposures

at NPPs (ICRP, 2007a). The recommended dose limits are as follows (ICRP, 2007a):

• For occupational exposure in planned exposure situations, the limit should be expressed as an effective dose of 20 mSv per year, averaged over defined five-year periods (100 mSv in five years), with the further provision that the effective dose should not exceed 50 mSv in any single year.

• For public exposure in planned exposure situations, the limit should be expressed as an effective dose of 1 mSv in a year. However, in special circumstances a higher value of effective dose could be allowed in a single year, provided that the average over defined five-year periods does not exceed 1 mSv per year.

The limits on effective dose apply to the sum of doses due to external exposures and committed doses from internal exposures due to intakes of radionuclides. Occupational intakes may be averaged over a period of five years to provide some flexibility. Similarly, averaging of public intakes over a period of five years would be acceptable in such special circumstances where averaging of the dose to members of the public could be allowed.

Finally, Table 11.9 presents the framework for recommended source — related dose constraints and reference levels with examples of constraints for workers and the public exposed to NPPs.

Several international organizations operate emergency centres partially or fully devoted to responding to nuclear or radiological emergencies. The IAEA operates the Incident and Emergency Centre as the global focal point for responding to nuclear and radiological emergencies under the terms established in the Conventions on Early Notification and Mutual Assistance. The Centre provides round-the-clock assistance to Member States and coordinates the drafting and publication of the IAEA standards and recommendations on emergency matters. The Centre also organizes training activities and international nuclear emergency exercises called ConvEx aimed at verifying international cooperation in responding to nuclear emergencies. Figure 12.5 shows the Incident and Emergency Centre of the International Atomic Energy Agency.

12.7.2 Regional and local emergency centres

Regional and local authorities have their own operations centres whose mission is to implement emergency operations. These centres, which in many cases are also the centres of non-nuclear emergency management, are endowed with specific media to stay permanently and securely connected with advanced command posts that are responsible for the implementation of countermeasures, as well as with other focal points, in order to:

• Receive the information sent by the operator’s emergency centre on the possible evolution of an emergency in the affected facility, and by the emergency centre of the regulatory body, giving technical recommenda­tions necessary to implement the appropriate emergency measures to protect the population

• Send orders to every intervention team

• Transmit operational information to local media

• Inform national authorities on the evolution of an emergency in the affected area and seek their help if they need means of intervention or extraordinary resources that are not available in the territory under the operator’s control.

12.5 Sources of further information and advice

Many national and international organizations related to nuclear energy, emergency management and radiation safety research have devoted efforts to issuing information on nuclear emergency matters. This information covers a wide range of topics, orientations, objectives and kinds of docu­ments, and can be consulted on the corresponding websites. In this regard:

• The IAEA, as mentioned above, has issued a number of safety stand­ards, recommendations and technical documents oriented at providing the Member States with adequate information for planning, prepared­ness and response to nuclear emergencies.

• The European Commission has contributed to the current knowledge of nuclear emergency management from a number of research projects carried out with its Framework Research Programmes during the last three decades. Significant results of these projects have been issued by the Commission and its associate research centres.

• The Nuclear Energy Agency has a Working Party on Nuclear Emergency Matters that acts as a forum for discussing development made by Member States on this subject.

• At national level, national emergency agencies and regulatory authori­ties permanently hold information and maintain programmes addressed to nuclear and radiological emergencies. These programmes include issuance of regulations, guidance and technical documents that are easily available directly from these institutions.

Radioactive waste is continuously generated during the operation of a nuclear power plant. Process waste comes from the continuous clean-up of the coolant that is circulated through the reactor core. It also comes from the control of releases of water and gas from the reactor facility. Clean-up is achieved by mechanically filtering the water and by ion exchange to demineralize the water. The purpose of the clean-up of the process water is to create a chemically benign environment to reduce corrosion and build­up of debris on the fuel (crud) and also to reduce the source for activation products that can spread through the reactor systems. The purpose of control of releases is to ensure that only small amounts of radioactivity, which are well within the regulatory limits, are released from the reactor facility. The primary waste products produced in the process waste are filter cartridges and sludge of ion exchange resins, other filter material and evap­orator concentrates. The filter cartridges can be handled in a similar way to other technological waste while the sludge needs solidification before further handling as waste. The activity concentration depends on the proc­esses used and the location of the filtering systems in the reactor. Particularly high activity would be found in the ion exchange resins in the primary system. The main radioisotopes are corrosion products, e. g. cobalt-60 and iron-55, and fission products, e. g. cesium-134, cesium-137 and strontium-90. The amount of fission products depends on the integrity of the fuel.

Technological and maintenance waste consists of exchanged components and material (e. g. paper, coveralls, discarded instruments, scaffolding and oils) that is used during maintenance. In most cases the activity concentra­tion is very low in technological and maintenance waste. It contains the same radioisotopes as the process waste. Some exchanged components can have higher activity concentration. This can be reduced by mechanical or chemical decontamination as it is mainly surface contamination.

Numerous studies routinely assess the current and future competitiveness of different electricity generating options under different scenario assump­tions. In a wide range of scenarios, nuclear power is a least-cost option for centralized base-load electricity generation (ENEF, 2010; NEA and IEA, 2010). The economic performance of nuclear power versus its alternatives is highly dependent on numerous factors such as the costs and availability of natural gas and coal, hydro power resources or wind availability, which allow direct comparisons only on a clearly defined case-by-case basis. Some studies question the economic competitiveness of nuclear energy usually by generalizing worst practices and denying future learning to nuclear power while assuming best practices and rapid future learning to non­nuclear alternatives, especially renewables (EREC and Greenpeace, 2010; WISE, 2009a, 2009b; Schneider et al., 2009).

In essence, because of the sometimes drastically divergent assumptions about the future driving forces of electricity demand and supply, technology and policy, the generating costs reported by these studies are unsuitable for comparisons. One exception is the already mentioned OECD report Projected Costs of Generating Electricity (NEA and IEA, 2010).

The OECD study calculates ‘levelized cost of electricity’ (LCOE) using two real discount interest rates, 5% and 10%,u applied to all technologies, harmonized generic technology performance assumptions and boundaries, and clearly specified fuel prices. For the first time, the study assessed the impact of a carbon price of $30 per tonne of carbon dioxide. The generating cost calculations, based on the simple levelized average (unit) lifetime cost approach based on the discounted cash flow (DCF) method, are summa­rized in Fig. 15.11.

The study reached two important conclusions. First, at low discount rates, capital-intensive generating technologies such as nuclear energy are among the least-cost baseload generating options. The actual merit order is location dependent and cannot be generalized.

An exception is provided by locations with lowest-cost coal availability, e. g. Australia or certain parts of the USA or (although not part of the OECD study by analogy) parts of China, India and other coal-rich develop­ing countries. Here coal, even when equipped with carbon capture, outper­forms nuclear power. A similar observation is valid for hydro power.

Second, at 10% discount rates, the competitiveness of nuclear power slips and fossil generation gains on nuclear power. In some locations, coal with and without carbon abatement as well as CCGT are least-cost generators. In others nuclear maintains its overall cost-competiveness.

The calculations highlight the paramount importance of discount rates, and to a lesser extent carbon and fuel prices when comparing different technologies (NEA and IEA, 2010).[97] [98]

15.11 Expected generating cost of different generating options (without carbon dioxide taxes): CSP=concentrating solar power, PV=photovoltaic, CCS = carbon capture and storage, IGCC = integrated gasification combined cycle. Adapted from NEA and IEA (2010).

The construction of a nuclear power plant can adversely affect the water quality and resources in the area through increased demand, the thermal impact of cooling water discharges and the disruption of designated habitats of ecological importance. Where these impacts are likely, applicants will need to ensure that their EIA identifies the existing levels of water quality, discharges and abstraction within the area, and the cumulative effect when considered with other industrial sites or projects existing or planned. Applicants are also required to set out the characteristics of cooling water for new nuclear power stations and the implications on marine and estua­rine environments, and will be expected to mitigate the hydrologic impacts of their activities.

18.2.2 Main decisions to be taken by the owner

The owner must take a number of decisions and make available important information to the team in charge of preparing the BIS before the latter can begin its work. Some of the most relevant information is the following:

• Owner (purchaser) identification

• Contractual approach

• Reactor type

• Number of units

• Power range (MWe) per unit and/or for the whole plant

• Plant location

• Site data

• Applicable codes, standards and regulatory requirements

• Cooling water system type

• Power grid characteristics

• Project schedule, including key milestones

• Licensing requirements and process to be followed

• Financing requirements of the project

• Scope of supply reserved to the owner

• Nuclear fuel (if required to be supplied by the plant vendor), and number of reloads to be supplied

• Quality management system requirements

• National participation policy

• Technology transfer objectives.

Operation of an NPP generates large quantities of radioactive material from the fission of nuclear fuel, and by neutron activation of reactor system fluids (during their passage through the reactor core) and of the structural materials in and around the reactor core. The radioactivity so generated must be confined or disposed of such that it does not cause undue radiation hazard to plant personnel, the public or to the environment. This objective is achieved by ensuring that the design, construction and operation of the NPP is performed using established industry and safety standards, and that the NPP is managed and operated by well-trained and qualified personnel following laid-down safety guidelines and procedures. As the operation of NPPs can pose radiation threats, the public and the environment have to be protected against these threats. Governments ensure this protection by only allowing the operation of NPPs under formal licenses.

For the purpose of licensing, the RB conducts a thorough review of all the phases in the life of the nuclear power plant. This may start with a formal appraisal of the technology to be deployed, continuing with an assessment of the site characteristics and the design and engineered safety features of the selected NPP, as well as specification of the safe operating envelope and other licensing conditions for operation of the NPP. The RB also maintains a careful oversight during the entire operational phase of the NPP by reviewing periodic reports, by making regulatory inspections and by other means to ensure that the licensing conditions are being complied with on a continuing basis. At the end of the plant’s operating life, the licensee ensures that the NPP is maintained in a safe state until its complete dis­mantling and decommissioning is taken up in accordance with the stipula­tions made by the RB. Finally, the RB reviews the decommissioning plan for the NPP and authorizes it if the requisite safety criteria are met, includ­ing those for disposal of radioactive waste arising from decommissioning activities.

Licensing for NPP siting, construction and operation 659